An installer has mounted a 51.2V LiFePO4 rack module and connected it to a hybrid inverter. The DC cables are fine and the battery powers on, but the inverter shows a BMS or battery communication alarm and no state of charge.
Start with the communication path, not the battery cells. Most of these faults come from one of four things: the cable is in the wrong port, the pinout doesn’t match, the protocol selected on the inverter doesn’t match the battery, or the master battery’s address or DIP setting is wrong. Check those in order before suspecting hardware.
Why it matters
With closed-loop communication, the inverter takes its charge and discharge limits and its state of charge from the BMS. Without it, the inverter may stop charging, raise an alarm, or fall back to voltage-only control. Redway’s PM-LV51200-5U and PM-LV51150-4U list RS485 and CAN-bus. Inverters named as compatible include Deye, Victron, GoodWe, Sol-Ark, SRNE, Solis, SAJ, Growatt, Luxpower, Voltronic, SMA and FOX.
Step-by-step check
- Port: confirm the cable runs from the battery’s designated inverter port (CAN or RS485) to the inverter’s BMS port, not to a monitoring or meter port.
- Pinout: RJ45 pin assignments differ between brands. Many inverters use a combined BMS port with CAN on one pair and RS485 on another. Compare both manuals and use the supplied or specified cable. Don’t assume a standard network cable will work.
- Protocol: select the matching battery protocol or brand setting on the inverter, and set the battery side to match if its protocol is selectable.
- Address: in a stack, set the module connected to the inverter as master, following the battery manual, and give the others unique addresses.
- Restart order: after changing DIP switches, power-cycle the battery so it reads the new address, then restart the inverter.
- Verify: the inverter should now show state of charge, cell or BMS data and charge limits.
Conditions and limits
Compatibility can depend on inverter firmware and BMS firmware versions. A brand appearing on a compatibility list doesn’t guarantee every model and firmware combination. Redway specifies a JBD BMS on these modules, but the protocol table for each inverter isn’t published on the product pages. Get it from Redway support for your inverter model.
Risk limits
Don’t run the system in lithium mode with high charge currents while communication is down unless the inverter’s voltage limits have been set conservatively to the battery datasheet values (58.4V maximum charge, 40V cut-off on these models). Turn off DC breakers before re-terminating cables. Our battery–inverter compatibility guide has more background.
Additional perspectives
When ordering rack batteries for a project, give the inverter model and firmware version in the RFQ and ask the supplier to confirm the protocol, cable pinout and DIP settings in writing. Ask for the matching communication cable to be included. Commissioning delays usually cost more than the cable does.
Redway Tech Editorial Team – Procurement perspective
If a site may change inverter brand later, prefer batteries offering both CAN and RS485, plus optional monitoring such as SNMP, Bluetooth or WiFi, which Redway lists as upgrades on some modules. Check the maximum parallel count (up to 16 on the PM-LV series) against your planned expansion so communication doesn’t limit growth.
Redway Tech Editorial Team – Selection perspective
Keep a commissioning record that includes the protocol setting, DIP addresses, firmware versions and a photo of the cable at both ends. Repeat the communication check after any inverter firmware update. Updates have been reported to change protocol behavior. If the fault returns intermittently, look for loose RJ45 latches or cables run alongside DC power leads.
Redway Tech Editorial Team – Maintenance perspective
Specifications are taken from Redway product pages as of October 2026. Where a figure isn’t published, this article says so. Confirm current specifications for your model with Redway before ordering. This article is general guidance, not a site-specific engineering assessment.
Related products
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- 51.2V 50Ah Rack-mounted Lithium LiFePO4 Battery Factory Wholesale (PM-LV5150-2U-PRO) 48V 50Ah
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